import java.util.Arrays;
import java.util.Scanner;

//输入一段字符串，把多余的字母删除例如：aasd 输出：asd
public class shanchuduoyvzimu {
    public static void main(String[] args) {
        Scanner in =new Scanner(System.in);
        String a=in.next();
        char[] b=a.toCharArray();
        for (int i = 0; i < b.length; i++) {
            for (int j = 0; j <b.length ; j++) {
                if(b[i]==b[j]){
                    b[i]=b[b.length-1];
                    b= Arrays.copyOf(b,b.length-1);
                }
            }
        }
        String c=String.valueOf(b);
        System.out.println(c);
    }
}
